Removed the hard brackets surrounding tuples in the debugger display … (#43389)

src/Scripting/CSharpTest/CommandLineRunnerTests.cs

@@ -235,7 +235,7 @@ public void Tuples()
             AssertEx.AssertEqualToleratingWhitespaceDifferences(
 $@"{LogoAndHelpPrompt}
 > (1,2)
-[(1, 2)]
+(1, 2)
 > ", runner.Console.Out.ToString());
         }
 

src/Scripting/CSharpTest/ObjectFormatterTests.cs

@@ -67,6 +67,20 @@ public void Objects()
             Assert.Equal(@"Sort { aB=-1, ab=1, Ac=-1, Ad=1, ad=-1, aE=1, aF=-1, AG=1 }", str);
         }
 
+        [Fact]
+        public void TupleType()
+        {
+            var tup = new Tuple<int, int>(1, 2);
+            Assert.Equal("(1, 2)", s_formatter.FormatObject(tup));
+        }
+
+        [Fact]
+        public void ValueTupleType()
+        {
+            (int, int) tup = (1, 2);
+            Assert.Equal("(1, 2)", s_formatter.FormatObject(tup));
+        }
+
         [Fact]
         public void ArrayMethodParameters()
         {

src/Scripting/Core/Hosting/ObjectFormatter/CommonObjectFormatter.Visitor.cs

@@ -9,6 +9,7 @@
 using System.Linq;
 using System.Reflection;
 using System.Runtime.CompilerServices;
+using Microsoft.Cci;
 using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.Scripting.Hosting
@@ -708,14 +709,48 @@ private void FormatMultidimensionalArrayElements(Builder result, Array array, bo
 
             #region Scalars
 
+            private bool IsTuple(object obj)
+            {
+#if NETSTANDARD2_0
+                if (obj is null)
+                {
+                    return false;
+                }
+
+                var type = obj.GetType();
+                if (!type.IsGenericType)
+                {
+                    return false;
+                }
+
+                int backtick = type.FullName.IndexOf('`');
+                if (backtick < 0)
+                {
+                    return false;
+                }
+
+                var nonGenericName = type.FullName[0..backtick];
+                return nonGenericName == "System.ValueTuple" || nonGenericName == "System.Tuple";
+#else
+                return obj is ITuple;
+#endif
+            }
+
             private void ObjectToString(Builder result, object obj)
             {
                 try
                 {
                     string str = obj.ToString();
-                    result.Append('[');
-                    result.Append(str);
-                    result.Append(']');
+                    if (IsTuple(obj))
+                    {
+                        result.Append(str);
+                    }
+                    else
+                    {
+                        result.Append('[');
+                        result.Append(str);
+                        result.Append(']');
+                    }
                 }
                 catch (Exception e)
                 {